19.LIstView使用（2）

最新推荐文章于 2022-12-14 16:49:43 发布

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本文介绍了一个使用 Android ListView 控件展示从 SQLite 数据库查询到数据的具体实现案例。通过自定义 Adapter 和布局文件，实现了列表项的数据绑定。

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总的布局文件

activity_main.xml

<LinearLayout 
	    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
	    android:id="@+id/ll"
	    android:layout_width="match_parent"
	    android:layout_height="match_parent"
	    android:paddingBottom="@dimen/activity_vertical_margin"
	    android:paddingLeft="@dimen/activity_horizontal_margin"
	    android:paddingRight="@dimen/activity_horizontal_margin"
	    android:paddingTop="@dimen/activity_vertical_margin"
	    tools:context=".MainActivity" >
	
	    <ListView 
	        android:id="@+id/lv"
		    android:layout_width="match_parent"
		    android:layout_height="match_parent"
	        ></ListView>
	
	</LinearLayout>

每一个条目的布局文件

item_listview.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
    
    <TextView
        android:id="@+id/tv_name"
        android:layout_width="wrap_content"
    	android:layout_height="wrap_content" 
    	android:text="名字"
    	android:textSize="25sp"
    	/>
    <LinearLayout
        android:layout_alignParentRight="true"
        android:layout_width="wrap_content"
    	android:layout_height="wrap_content" 
    	android:orientation="vertical"
        >
        <TextView
        android:id="@+id/tv_salary"
        android:layout_width="wrap_content"
    	android:layout_height="wrap_content" 
    	android:text="号码"
    	android:textSize="25sp"
    	/>
        <TextView
        android:id="@+id/tv_phone"
        android:layout_width="wrap_content"
    	android:layout_height="wrap_content" 
    	android:text="工资"
    	android:textSize="25sp"
    	/>
    </LinearLayout>
    
 
</RelativeLayout>

逻辑代码

MainActivity.java

public class MainActivity extends Activity {
 
	List<Person> personList;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        personList = new ArrayList<Person>();
        //把数据库的数据查询出来
        MyOpenHelper oh = new MyOpenHelper(this, "person.db", null, 1);
        SQLiteDatabase db = oh.getWritableDatabase();
        Cursor cursor = db.query("person", null, null, null, null, null, null, null);
        
        while(cursor.moveToNext()){
        	String _id = cursor.getString(0);
        	String name = cursor.getString(1);
        	String phone = cursor.getString(2);
        	String salary = cursor.getString(3);
        	
        	Person p = new Person(_id, name, phone, salary);
        	personList.add(p);
        }
        
        ListView lv = (ListView) findViewById(R.id.lv);
        lv.setAdapter(new MyAdapter());
    }
    
    class MyAdapter extends BaseAdapter{
 
		@Override
		public int getCount() {
			// TODO Auto-generated method stub
			return personList.size();
		}
 
		@Override
		public Object getItem(int position) {
			// TODO Auto-generated method stub
			return null;
		}
 
		@Override
		public long getItemId(int position) {
			// TODO Auto-generated method stub
			return 0;
		}
		//由系统调用，获取一个View对象，作为ListView的条目
		//position本次getView方法调用返回的view对象，在listView中处于第几个条目，convertview是缓存机制
		@Override
		public View getView(int position, View convertView, ViewGroup parent) {
			Person p = personList.get(position);
			// TODO Auto-generated method stub
			//TextView tv = new TextView(MainActivity.this);
			//Person p = personList.get(position);
			//System.out.println("position" + position);
			//tv.setText(p.toString());
			System.out.println("getView()调用" + position);
			
			View v = null;
			//判断是否条目是否缓存
			if(convertView == null){
				//如果没缓存填充新的对象，
				v = View.inflate(MainActivity.this, R.layout.item_listview, null);
			}else{
				v = convertView;
			}
			
			//方法1：把布局文件填充成一个view对象
			//v = View.inflate(MainActivity.this, R.layout.item_listview, null);
			
			//方法2：获取布局填充器对象
			//LayoutInflater inflater = LayoutInflater.from(MainActivity.this);
			//View v2 = inflater.inflate(R.layout.item_listview, null);
			
			//方法3：
			LayoutInflater inflater2 = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE );
			View v3 = inflater2.inflate(R.layout.item_listview, null);
			
			TextView tv_name = (TextView) v.findViewById(R.id.tv_name);
			TextView tv_phone = (TextView) v.findViewById(R.id.tv_phone);
			TextView tv_salary = (TextView) v.findViewById(R.id.tv_salary);
			tv_name.setText(p.getName());
			tv_phone.setText(p.getPhone());
			tv_salary.setText(p.getSalary());
			return v;
		}
    	
    }